The present invention relates to a hydraulic cement admixture capable of enhancing the latter stage set strength of the resultant cured composition.
The term cement is used to designate many different kinds of materials useful as binders or adhesives. Hydraulic cements are powdered materials which, when mixed with water, form a "paste" that hardens slowly. If further mixed with fine aggregate (e.g. sand), it forms a "mortar", and if mixed with fine and coarse aggregate (e.g. sand and stone) it forms a "concrete," which are rock-hard products. These products are commonly referred to as hydraulic cement compositions or mixes. These compositions are commonly formed from Portland cement (conforms to ASTM C-150), blended cements (having large amounts of slags, pozzolanic materials and the like) as well as other hydratable cements.
Various additives have been used in hydraulic cement compositions to alter mixing, curing or hardened properties. Thus, lignin sulfonates and naphthalene sulfonate-formaldehyde condensates have been used to increase the fluidity of hydraulic cement compositions to which water has been admixed. Cellulosic polymers and bentonite clay have been used to control sedimentation of particles in pastes and mortar compositions. Fumed silica has been used as an additive to make stronger concrete with reduced permeability. Inorganic salts such as metal chlorides (e.g. sodium chloride, potassium chloride) and nitrites (e.g. calcium nitrite) are added to accelerate the set of the concrete mass. Various lower alkanolamines such as monoethanolamine, diethanolamine and triethanolamine and the like, have been used as set accelerators. Trialkanolamines of higher content have been found to increase later age compressive strength of certain cement compositions having high C.sub.4 AF content.
It is desired to have materials which can be added to hydraulic cement compositions in low dosages to achieve enhanced later age set strength.